Mechanical blade locks



P 26, 1967 1.. vAccA ETAL 3,343,610

MECHANI CAL BLADE LOCKS Filed June 29, 1965 2 Sheets-Sheet 1 INVENTORS LU/Gl VAGGA BLADE FOLDED BLADE LOOKED DONALD L. FERR/8 BY MWAW ATTORNEY Sept. 26, 1967 L. VACCA ETAL MECHANICAL BLADE LOCKS 2 Sheets-Sheet 2 Filed June 29, 1965 v RD I 1/ l e United States Patent 3,343,610 MECHANICAL BLADE LOCKS Luigi Vacca, Milford, and Donald L. Ferris, Newton, Conn., assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed June 29, 1965, Ser. No. 468,171 3 Claims. (Cl. 170-16012) This invention relates to a mechanism for locking the folded blade of a helicopter in blade folded position.

It has been the custom to maintain the blades of a helicopter rotor in folded position by holding the operating piston in its end position through the hydraulic pressure on the piston. The difiic-ulty in this method has been the necessity of inspection for leaks in the hydraulic system and the possibility of the development of a leak after an inspection which would allow the piston to move from its end position and release the blade from its locked position. The inclusion of a mechanical locking means must be such as not to interfere with the normal operation of the helicopter blade.

It is an object of the present invention to provide a mechanical locking mechanism which will be positive in action and will lock the folded blades of a helicopter without possibility of release until release is desired.

It is a further object of the present invention to provide a pair of gear segments which will move the blade to locking position and when in locking position will lock the folded blade against movement.

It is a still further object of the present invention to provide a mechanical mechanism attached to the folded blades of a helicopter, said mechanism being a gear segment secured to the blade and in mesh with another gear segment and to drive the meshed gear segment to a locking position and when in locking position to lock the gear segments against movement by a lever and link mechanism which is moved to a position beyond a straight line position and locked in that position by the integral construction of one of the gear segments.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a plan view of the locking mechanism showing the blade folded and locked;

FIG. 2 is a plan view of the locking mechanism with the blade folded and the link-lever mechanism in the position of opening; and

FIG. 3 is a plan view of the locking mechanism with the blade unfolded, in flight position and the locking mechanism inoperative.

Referring to the drawings wherein like numerals refer to like parts throughout the several views, only those parts of the mechanical locking mechanism needed to show the invention are illustrated, the operating piston and the locking pin, not shown.

A helicopter blade 11 has a gear segment 12 mounted thereon. This gear segment is in mesh with another gear segment 13 hereinafter referred to as the driving gear 13. This driving gear 13 is journaled for partial rotation on axis 14 carried by the housing 15. Also carried by the axis 14 is a cam 16 which moves with the driving gear.

The housing pivotally supports a crank lever 17 which carries at the end of its short leg 18, a cam follower 19. The long leg 21 of the crank lever is formed at its end with a lateral projection 22 having a fiat face 23 normal to the longitudinal dimension of the long leg 21 of the crank lever. The end of the long leg 21 is fitted with a pin 24 on which is mounted a link member 25.

3,343,6 l0 Patented Sept. 26, 1967 The link member 25, at the crank lever end is formed with a lateral projection 26 similar to the projection 22 and which projection 26 is further formed with a flat face 27 adapted to contact the fiat face 23 of the projection 22 and provide a stop for limiting the movement of the crank link-lever combination. The free end of the link 25 is pivotally attached to the gear segment 12.

A spring 28 is attached to the pin 24 to bias the crank link-lever combination to a projection face contacting position, which is the locked position of the folded blade.

The driving gear 13 is formed with an enlarged space 29 located between the last tooth 31 and its adjacent tooth 32. The enlargement of this space permits movement of the driving gear through a slight are without movement of the meshed gear segment 12. This extra motion of the driving gear moves the link-crank lever V is accomplished by a hydraulically operated piston, not

shown, but of any usual construction, in a counter-clockwise direction swings the crank link-lever combination to the position shown in FIG. 2, with the cam 16 riding past the cam follower 19, the crank lever-link combination just short of a straight line position and the nextto-last tooth 34 of the blade supported gear segment just leaving the face of the tooth 32 of the driving gear. The next small incremental movement of the driving gear moves the driving gear without moving the driven gear segment 12 by reason of the space 29 between the teeth 31 and 32 of the driving gear. This small movement moves the crank lever-link combination to the straight line position, and beyond, to securely lock the mechanism in locking position (FIG. 3) with the faces of the projections in contact. Driving gear 13 and the tooth 34 of the driven gear segment are also in contact and the crank link-lever combination held in a position beyond the straight line position by the spring 28 as shown in FIG. 1.

The folded blade 11 is now securely locked in folded position by a mechanical mechanism which needs no attention and which will secure the blade against movement until rotation of the driving gear releases it.

The return of the folded blade to operating position is accomplished by rotating the driving gear in the opposite direction. The enlargement of the space between teeth 31 and 32 of the driving gear 13 allows movement of that gear segment independent of the driven gear 12. This first free movement of gear segment 13 provides the means for unlocking the crank link-lever combination which is necessary in order to free gear segment 12. If the crank link-lever combination was not swung into an unlocked position, the gear teeth would mesh, creating a load on the teeth, and the crank link-lever combination would be forced into a further locked position. During the free clockwise rotation of gear segment 13, cam 16, acting on cam follower 19, moves the crank link-lever combination from its 0fl-center position shown in FIG. 1 into and beyond the straight line position as shown in FIG. 2. Further movement of gear segment 13 in a clockwise direction brings the second tooth 32 into contact with the tooth 33 of the gear segment 12 and starts the movement of the gear segment. Further rotation of the driving gear moves the folded blade to operative position shown in FIG. 3. It is the independent movement of the driving gear, accomplished through the enlargement of the space between the last two teeth which permits the crank link-lever combination to move to the locking position and securely lock the gear segment 12 in a position where the teeth are not in mesh with thedriving gear. The unlocking movement may not be accomplished through any movement of the gear segment 12 as it is securely locked until there is that initial movement of the driving gear to bring the teeth back into mesh.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A mechanism for locking the folded blade of a helicopter comprising a gear segment mounted for pivotal movement through a predetermined are, said gear segment being attached to the base of a helicopter blade;

a driving gear segment in mesh with said blade carrying gear segment, said driving gear segment being mounted for limited pivotal movement;

a crank lever mounted for pivotal movement and formed with a cam follower at the end of its short leg and a projection adjacent the end of its long a cam carried by and rotating with said driving gear segment, said cam being adapted to engage said cam follower during the initial pivotal movement of said driving gear in the unlocking operation;

a link pivoted at one endto the long end of said crank lever and being pivotally mounted at the other end to the blade carrying gear segment, said link being 4 formed at its crank lever end with a projection adapted to engage the projection of the crank lever; spring means attached to the juncture of the link and crank lever to bias the movement of the lever and link in one direction, said levers being moved by the combined movement of the driving gear segment and, the blade carrying gear segment to a straight line position; and means integral with the driving gear permitting additional movement of the driving gear without corresponding movement of the blade carrying gear segment to permit movement of the lever and link to a position beyond the straight line position to bring the projections into contact and lock the blade and blade carrying gear segment in blade folded position.

2. A mechanism for locking the folded blade of a helicopter according to claim 1 wherein the projection of the crank lever and the projection of the link are formed with contacting faces adapted to engage one with the other when the crank link-lever combination is in the locking position.

3. A mechanism for locking the folded blade of a helicopter according to claim 1 wherein the means integral with the driving gear is an increased distance between the last tooth and its adjacent tooth on the driving gear.

No references cited.

MARTIN P. SCHWADRON, Primary Examiner.

E. A. POWELL, JR., Assistant Examiner. 

1. A MECHANISM FOR LOCKING THE FOLDED BLADE OF A HELICOPTER COMPRISING A GEAR SEGMENT MOUNTED FOR PIVOTAL MOVEMENT THROUGH A PREDETERMINED ARC, SAID GEAR SEGMENT BEING ATTACHED TO THE BASE OF A HELICOPTER BLADE; A DRIVING GEAR SEGMENT IN MESH WITH SAID BLADE CARRYING GEAR SEGMENT, SAID DRIVING GEAR SEGMENT BEING MOUNTED FOR LIMITED PIVOTAL MOVEMENT; A CRANK LEVER MOUNTED FOR PIVOTAL MOVEMENT AND FORMED WITH A CAM FOLLOWER AT THE END OF ITS SHORT LEG AND A PROJECTION ADJACENT THE END OF ITS LONG LEG; A CAM CARRIED BY AND ROTATING WITH SAID DRIVING CAM SEGMENT, SAID CAM BEING ADAPTED TO ENGAGE SAID CAM FOLLOWER DURING THE INITIAL PIVOTAL MOVEMENT OF SAID DRIVING GEAR IN THE UNLOCKING OPERATION; A LINK PIVOTED AT ONE END TO THE LONG END OF SAID CRANK LEVER AND BEING PIVOTALLY MOUNTED AT THE OTHER END TO THE BLADE CARRYING GEAR SEGMENT, SAID LINK BEING FORMED AT ITS CRANK LEVER END WITH A PROJECTION ADAPTED TO ENGAGE THE PROJECTION OF THE CRANK LEVER; SPRING MEANS ATTACHED TO THE JUNCTURE OF THE LINK AND CRANK LEVER TO BIAS THE MOVEMENT OF THE LEVER AND LINK IN ONE DIRECTION, SAID LEVERS BEING MOVED BY THE COMBINED MOVEMENT OF THE DRIVING GEAR SEGMENT AND THE BLADE CARRYING GEAR SEGMENT TO A STRAIGHT LINE POSITION; AND MEANS INTEGRAL WITH THE DRIVING GEAR PERMITTING ADDITIONAL MOVEMENT OF THE DRIVING GEAR WITHOUT CORRESPONDING MOVEMENT OF THE BLADE CARRYING GEAR SEGMENT TO PERMIT MOVEMENT OF THE LEVER AND LINK TO A POSITION BEYOND THE STRAIGHT LINE POSITION TO BRING THE PROJECTIONS INTO CONTACT AND LOCK THE BLADE AND BLADE CARRYING GEAR SEGMENT IN BLADE FOLDED POSITION. 